Rina S.

Any of a series of hollow carbon molecules connected by single or double bonds and form a closed cage (buckyballs) or a cylinder (carbon 'nanotubes') is called Fullerene. These compounds have superconducting properties. The first Fullerene was discovered in 1985 by Sir W. Kyoto.
In diamond, each carbon atom is linked with four neighbouring carbon atoms held at the corners of a regular tetrahedron by covalent bonds. The C-C bonds are powerful, so crystal of diamond is the hardest substance on earth.
In graphite, the carbon atoms are arranged in regular hexagons in flat parallel layers. There is no strong bonding between different layers, which are therefore easily separable from each other. Whilst the bonds within the layers are strong, those between the layers are not, and so they slide over each other easily. Hence graphite has the softness and lubricating properties.